Determination of the Bending Modulus in Microemulsions by Using the Dynamic Kerr Effect

We have determined the value of the bending modulus k in w/o (decaline)‐microemulsions using the dynamic Kerr effect. The relaxation of the electrically induced birefringence in a dilute w/o‐microemulsion corresponds to the relaxation of the individual nanodroplets towards their spherical form. The experimental results were described by using a theory for the dynamics of a microemulsion droplet; two cases are discussed: (i) a model in which a constant mean excess surface area during relaxation has been assumed and (ii) where a variable surface area has been considered. For a polydispersity in droplet size of 30%, we find k = 0.4 kBT (± 20%). This is in accordance with findings using the static Kerr effect.